I don't think any net is going to actually "block" the light from your plants, but the finer-mesh nets like mosquito netting will probably filter it somewhat. I don't know if it would be enough to make any difference, though. I'm guessing it would have the same effect as if the sky was very slightly overcast or hazy every day, but like i say, that's just a guess. And even if i'm right, I'm not sure how much difference it would make.
Where I do think you're going to run into problems is with the box itself. Unless I'm missing your point, you plan on growing the plants inside the box all season, right? If that's the case, you're going to need a pretty tall box, and if you're worried about concealment I think you'd be a lot more concerned about someone spotting a 6-foot tall box out in the middle of the boonies than someone spotting, say, some plants out in the middle of several hundred million other plants of various sizes and colors. Secondarily, if you do have your plants in a box that tall, the sides of the box are going to block almost all direct light to your plants. They'll be in shadow all day long.
With all due respect, I think you may be overthinking this. Just stick the suckers out in the middle of the sticks, and count on nobody stumbling across them. Cripes, there were times last year where I was standing 10 feet away from one of my plants, and I still couldn't find the damned thing - and i knew exactly what I was looking for, because I was the one who planted it. Unless someone is specifically prowling around looking for marijuana, they're usually not going to notice one even if they trip over it - but I pretty much guarantee you that anyone who sees a box in the middle of a-million-miles-from-nowhere is going to head straight over to have a peek inside.